The End of Braking...
08-12-2012, 02:17 PM
#31
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Rennlist Member
Rennlist Member
Boy this topic has me thinking.
I try to use as little brake as possible and use tires to scrub speed so I can get on throttle sooner. Perhaps this comes from my karting days when I was following the Rotax national champion around the track and I would see him slightly lock up the rears and turn in at the same time and then on the gas. If course in a kart you are always blending the brakes and gas to balance the kart.
I try to use as little brake as possible and use tires to scrub speed so I can get on throttle sooner. Perhaps this comes from my karting days when I was following the Rotax national champion around the track and I would see him slightly lock up the rears and turn in at the same time and then on the gas. If course in a kart you are always blending the brakes and gas to balance the kart.
08-12-2012, 02:45 PM
#32
Burning Brakes
Nice thread, but I think most people trying to learn would just be confused if they read it from start to finish. Not to mention, I think the approach to braking and getting to the apex changes based on experience/skill level. I know for me, I've gone through probably 3 different "phases" while always having the goal of simply trying to do whatever would result in a faster lap time.
Personally, I keep things simple: At all points on the race track I want to use up all the available grip at the front and rear of the car. When I first started, I still had the same goal, but I didn't realize there was so many areas around a lap where I was only using up one end (or neither) of the car. That's been the difference between going fast, and really fast, and fastest of the fast (which I'm still working on!).
The most basic and fundamental way I've found to monitor and compare this (and it's the same for all corners), is by using data analysis software and studying the longitudinal and latitudinal G channels. If you use something like Motec normally, you can create a nifty little math channel of your own which is simply the vector sum of both G channels. Or the old fashioned way, and just graph long/lat G next to each other. What I look for is to make sure there's no dip in my transition from longitudinal load (braking) to lateral (turning). Here's an example from my last test day (yellow vertical line is turn-in point):
I'm the white line, JvO is the red line. The important channel (IMO) to look at for this discussion is the GLOAD (second to bottom) -- it's the vector sum of both the long and lat G channel and is basically plotting the total G load through the tires at any given time. Notice how there is no dip in GLOAD, from the time we go to the brakes to well after full-throttle and we're tracked out down the GLOAD drop. Also notice how early in the turn-in process (Steering Wheel Angle channel) the long and lat G channels cross-over, yet, the GLOAD channel stays flat. IMO, that's the real transition period... not when I begin to turn-in.
For most slower guys (and myself included while I was learning) there's an obvious dip in the transition from braking through the turn-in point down to the apex.
There really isn't a difference in what I look for between different corners at any tracks.. If I have to slow the car down (either by lifting, braking, and/or downshifting), I want the G loads to look the same which means I'm using up all the car at all points in time (where I'm not at 100% throttle).
Now, I wouldn't necessarily ask a novice to worry about this but if we're talking about driving the car as fast as it will possibly go around a track, I've found it useful. :-)
-mike
Personally, I keep things simple: At all points on the race track I want to use up all the available grip at the front and rear of the car. When I first started, I still had the same goal, but I didn't realize there was so many areas around a lap where I was only using up one end (or neither) of the car. That's been the difference between going fast, and really fast, and fastest of the fast (which I'm still working on!).
The most basic and fundamental way I've found to monitor and compare this (and it's the same for all corners), is by using data analysis software and studying the longitudinal and latitudinal G channels. If you use something like Motec normally, you can create a nifty little math channel of your own which is simply the vector sum of both G channels. Or the old fashioned way, and just graph long/lat G next to each other. What I look for is to make sure there's no dip in my transition from longitudinal load (braking) to lateral (turning). Here's an example from my last test day (yellow vertical line is turn-in point):
I'm the white line, JvO is the red line. The important channel (IMO) to look at for this discussion is the GLOAD (second to bottom) -- it's the vector sum of both the long and lat G channel and is basically plotting the total G load through the tires at any given time. Notice how there is no dip in GLOAD, from the time we go to the brakes to well after full-throttle and we're tracked out down the GLOAD drop. Also notice how early in the turn-in process (Steering Wheel Angle channel) the long and lat G channels cross-over, yet, the GLOAD channel stays flat. IMO, that's the real transition period... not when I begin to turn-in.
For most slower guys (and myself included while I was learning) there's an obvious dip in the transition from braking through the turn-in point down to the apex.
There really isn't a difference in what I look for between different corners at any tracks.. If I have to slow the car down (either by lifting, braking, and/or downshifting), I want the G loads to look the same which means I'm using up all the car at all points in time (where I'm not at 100% throttle).
Now, I wouldn't necessarily ask a novice to worry about this but if we're talking about driving the car as fast as it will possibly go around a track, I've found it useful. :-)
-mike
08-12-2012, 03:18 PM
#34
Burning Brakes
Looking at my own data, I can always tell if I'm not carrying enough speed on entry because I'll get 10-25% throttle at or before the apex to makeup for the over slowing. The faster I'm getting, the more I'm coasting. :-)
-mike
08-12-2012, 04:08 PM
#36
I suspect if you look at the data, the less power a car has the less trail braking is going on and the sooner the throttle is applied. My point is that you can't make blanket statements (I was guilty of this earlier in the thread) about trail braking and how soon throttle is applied. You have to consider the power of the car. What makes sense for a Cup Car probably isn't what makes sense for a car that cannot accelerate nearly as quickly.
Here is some text from "Going Faster" regarding the Throttle Application Point that makes sense to me:
As a rule, the throttle application point is where you can begin acceleration and still make the corner. If you have to feather the throttle at the exit of the corner to stay on [the track], then you have begun acceleration too early.
So generally, the less acceleration potential a car has, the sooner it can get on the gas.
Scott
Here is some text from "Going Faster" regarding the Throttle Application Point that makes sense to me:
As a rule, the throttle application point is where you can begin acceleration and still make the corner. If you have to feather the throttle at the exit of the corner to stay on [the track], then you have begun acceleration too early.
So generally, the less acceleration potential a car has, the sooner it can get on the gas.
Scott
08-12-2012, 04:18 PM
#38
Burning Brakes
I suspect if you look at the data, the less power a car has the less trail braking is going on and the sooner the throttle is applied. My point is that you can't make blanket statements (I was guilty of this earlier in the thread) about trail braking and how soon throttle is applied. You have to consider the power of the car. What makes sense for a Cup Car probably isn't what makes sense for a car that cannot accelerate nearly as quickly.
So generally, the less acceleration potential a car has, the sooner it can get on the gas.
Scott
So generally, the less acceleration potential a car has, the sooner it can get on the gas.
Scott
-mike
08-12-2012, 04:32 PM
#39
Nordschleife Master
I won't derail this thread, it's a very valuable discussion, and yes there are always compromises for particular corners but it is an absolute that if you are applying power (not just maintenance throttle to balance the chassis) before the apex you've scrubbed too much speed. You could be faster.
However, it was one afternoon with Michael Petiford where it went from being an idea that I understood to something that had more intuitive meaning in my attempts to go fast and was where I first understood the idea of the end of braking. Driving back to back sessions in my car (not my 911, my Subaru) what I witnessed when Michael took the wheel was that not only was he starting his braking later than I was starting mine, but that he was releasing his braking later than I was. Because I was overbraking, I was trying to compensate with earlier throttle, which in a Subaru generally results in poor corner rotation and push. It was during those laps watching Michael that I realized that my point of brake release was relevant to my corner entry speed. Prior to that I had thought strictly in terms of where do I start braking and where do I start using throttle. Ever since then, I've thought in terms of when do I end my braking in addition to when do get on throttle. They are totally tied together.
08-12-2012, 04:34 PM
#40
Rennlist Member
I suspect if you look at the data, the less power a car has the less trail braking is going on and the sooner the throttle is applied. My point is that you can't make blanket statements (I was guilty of this earlier in the thread) about trail braking and how soon throttle is applied. You have to consider the power of the car. What makes sense for a Cup Car probably isn't what makes sense for a car that cannot accelerate nearly as quickly.
Here is some text from "Going Faster" regarding the Throttle Application Point that makes sense to me:
As a rule, the throttle application point is where you can begin acceleration and still make the corner. If you have to feather the throttle at the exit of the corner to stay on [the track], then you have begun acceleration too early.
So generally, the less acceleration potential a car has, the sooner it can get on the gas.
Scott
Here is some text from "Going Faster" regarding the Throttle Application Point that makes sense to me:
As a rule, the throttle application point is where you can begin acceleration and still make the corner. If you have to feather the throttle at the exit of the corner to stay on [the track], then you have begun acceleration too early.
So generally, the less acceleration potential a car has, the sooner it can get on the gas.
Scott
I think the ability to get into the throttle has to do with grip and balance and the question of whether or not you're going to upset the car in terms of grip and direction. If you're at the limit of grip mid-arc and are coasting or maintaining throttle, it doesn't matter what degree of 'acceleration potential' you have.
Perhaps torque, LSD, and right foot feel are a factor about how you feed the throttle in
08-12-2012, 04:49 PM
#41
What part don't you agree with?
Here is a quote in "Going Faster" from Jeremy Dale:
The amount you trail-brake into a corner really changes with the type of car you're driving. With a low powered car with a lot of grip, like a Formula Vee on slicks, there's not a lot of braking and turning because in most corners you're on the power so early in the corner. In the WSC car, for example, you use it a lot because with so much horsepower you can't get to the power early so you decelerate deeper into the corner.
My race car has a lot of grip and is medium powered (8.33 lbs per HP). I would expect it to trail brake less than a Cup Car and get on the gas a little sooner in a corner.
Scott
Here is a quote in "Going Faster" from Jeremy Dale:
The amount you trail-brake into a corner really changes with the type of car you're driving. With a low powered car with a lot of grip, like a Formula Vee on slicks, there's not a lot of braking and turning because in most corners you're on the power so early in the corner. In the WSC car, for example, you use it a lot because with so much horsepower you can't get to the power early so you decelerate deeper into the corner.
My race car has a lot of grip and is medium powered (8.33 lbs per HP). I would expect it to trail brake less than a Cup Car and get on the gas a little sooner in a corner.
Scott
08-12-2012, 05:00 PM
#42
Burning Brakes
I didn't agree with any of the parts I quoted. :-)
Saying you don't trail brake as much in a slower/lower horse power car is just fundamentally wrong. You might not trail brake as much as a higher horsepower/faster car on the same track, but it's not because the car is slower or has less power. Put the same 2 cars on a track tight enough where the slower car still has to brake for most of the corners and the technique applied to go fast is going to be the same.
The biggest difference, IMO, switching between slower cars and faster cars (I drove in a Spec E30 in last years 25 Hours of Thunderhill) is with the slower cars you *must* carry more speed in on entry and quite frankly, the application of throttle in the middle to exit means little (because the power output is so small and it's effect on the car is so little). It's why I don't believe a Spec Miata or a Spec E30 is the "perfect" car to learn in (albeit, very good). You won't learn all the skills/technique you'll need to survive in a faster car. You'll have to move to a faster car to learn them.
-mike
Saying you don't trail brake as much in a slower/lower horse power car is just fundamentally wrong. You might not trail brake as much as a higher horsepower/faster car on the same track, but it's not because the car is slower or has less power. Put the same 2 cars on a track tight enough where the slower car still has to brake for most of the corners and the technique applied to go fast is going to be the same.
The biggest difference, IMO, switching between slower cars and faster cars (I drove in a Spec E30 in last years 25 Hours of Thunderhill) is with the slower cars you *must* carry more speed in on entry and quite frankly, the application of throttle in the middle to exit means little (because the power output is so small and it's effect on the car is so little). It's why I don't believe a Spec Miata or a Spec E30 is the "perfect" car to learn in (albeit, very good). You won't learn all the skills/technique you'll need to survive in a faster car. You'll have to move to a faster car to learn them.
-mike
08-12-2012, 05:02 PM
#43
I suspect if you look at the data, the less power a car has the less trail braking is going on and the sooner the throttle is applied. My point is that you can't make blanket statements (I was guilty of this earlier in the thread) about trail braking and how soon throttle is applied. You have to consider the power of the car. What makes sense for a Cup Car probably isn't what makes sense for a car that cannot accelerate nearly as quickly.
Here is some text from "Going Faster" regarding the Throttle Application Point that makes sense to me:
As a rule, the throttle application point is where you can begin acceleration and still make the corner. If you have to feather the throttle at the exit of the corner to stay on [the track], then you have begun acceleration too early.
So generally, the less acceleration potential a car has, the sooner it can get on the gas.
Scott
Here is some text from "Going Faster" regarding the Throttle Application Point that makes sense to me:
As a rule, the throttle application point is where you can begin acceleration and still make the corner. If you have to feather the throttle at the exit of the corner to stay on [the track], then you have begun acceleration too early.
So generally, the less acceleration potential a car has, the sooner it can get on the gas.
Scott
Hmm, don't think so. Semantics are always challenging
I think the ability to get into the throttle has to do with grip and balance and the question of whether or not you're going to upset the car in terms of grip and direction. If you're at the limit of grip mid-arc and are coasting or maintaining throttle, it doesn't matter what degree of 'acceleration potential' you have.
Perhaps torque, LSD, and right foot feel are a factor about how you feed the throttle in
I think the ability to get into the throttle has to do with grip and balance and the question of whether or not you're going to upset the car in terms of grip and direction. If you're at the limit of grip mid-arc and are coasting or maintaining throttle, it doesn't matter what degree of 'acceleration potential' you have.
Perhaps torque, LSD, and right foot feel are a factor about how you feed the throttle in
"So generally, the less acceleration potential a car has, the sooner it can get on the gas [in the corner] without having to feather the throttle on corner exit."
I was talking about what we should be attempting to do in the corner. You are talking about the mechanics of being able to do it.
Scott
08-12-2012, 05:12 PM
#44
What about this text from "Going Faster":
You will find that, for the same corner, lower powered cars will have earlier throttle-application points than cars with more horsepower and greater acceleration potential.
Is that all wrong too?
I am not sure how motorcycles apply here, but I certainly trail braked later and got on the throttle later on my 1000cc 190 HP bike than I did on my 600cc 120 HP bike. I learned how that worked from an AMA Pro that rode both 600cc Supersport and 1000cc Superbike bikes.
Scott
08-12-2012, 05:16 PM
#45
Burning Brakes
I just want to add, I really think the advice/tips/guidance given on this subject ultimately depends on the current experience/speed of the person trying to apply them. I think that's why it's so important to get a good coach who can personally work with you -- they can figure out where you are and hopefully give the correct advice for the situation.
It's all to easy to hear a tip from a Pro or read something in a book that only applies to the last 0.01% of pace throughout a corner. When honestly, the person trying to apply it still hasn't gotten the other 1-2% out of the corner yet (goes for me as well, i'm not directing this at anyone particular). :-)
-mike
It's all to easy to hear a tip from a Pro or read something in a book that only applies to the last 0.01% of pace throughout a corner. When honestly, the person trying to apply it still hasn't gotten the other 1-2% out of the corner yet (goes for me as well, i'm not directing this at anyone particular). :-)
-mike